Effect and Characterization of Stone–Wales Defects on Graphene Quantum Dot: A First-Principles Study

Condensed Matter

Jana, Debnarayan¹  Chakraborti (Banerjee), Gargi²  Bandyopadhyay, Arka³ 

[1] Author to whom correspondence should be addressed.;Department of Physics, St. Thomas’ College of Engineering Technology, 4, Diamond Harbour Road, Kidderpore, Kolkata 700023, India;Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, India

关键词: density functional theory (DFT);    Raman spectroscopy;    Stone–Wales defect;    electronic properties;    infra-red spectra;   

DOI  :  10.3390/condmat3040050

学科分类：凝聚态物理

来源: mdpi

【 摘 要 】

A first principles based density functional theory (DFT) has been employed to identify the signature of Stone–Wales (SW) defects in semiconducting graphene quantum dot (GQD). Results show that the G mode in the Raman spectra of GQD has been red shifted to 1544.21 cm− 1in the presence of 2.08% SW defect concentration. In addition, the intensity ratio between a robust low intense contraction–elongation mode and G mode is found to be reduced for the defected structure. We have also observed a Raman mode at 1674.04 cm− 1due to the solo contribution of the defected bond. The increase in defect concentration, however, reduces the stability of the structures. As a consequence, the systems undergo structural buckling due to the presence of SW defect generated additional stresses. We have further explored that the 1615.45 cm− 1Raman mode and 1619.29 cm− 1infra-red mode are due to the collective stretching of two distinct SW defects separated at a distance 7.98 Å. Therefore, this is the smallest separation between the SW defects for their distinct existence. The pristine structure possesses maximum electrical conductivity and the same reduces to 0.37 times for 2.08% SW defect. On the other hand, the work function is reduced in the presence of defects except for the structure with SW defects separated at 7.98 Å. All these results will serve as an important reference to facilitate the potential applications of GQD based nano-devices with inherent topological SW defects.

【 授权许可】

CC BY